#include <iostream>

void Swap(int &a,int &b)
{
    int temp = a;
    a = b;
    b = temp;
}

int main()
{
    int a = 10;
    int b = 20;
    //for(int i = 0;i < 4;i++)
    Swap(a,b);
        std::cout<<b<<std::endl;

    return 0;
}